For many workshops, especially longer workshops spanning many days, planting a tree can be a wonderful ritual to bond a group, do something for peace with the earth, and provide a great photo opportunity. If the group is international you can invite participants to bring their national or indigenous dress and flags to celebrate the diversity of the group and provide a delightful colorful experience. A tree planting also leaves something permanent at the training venue. Many times we’ve had participants go back to visit that venue and report about how the tree is doing.
We let the participants form a committee to plan the ritual which gives more ownership for the group to the entire event. The tree plantings always become one of the highlights of the entire training.